全文获取类型
收费全文 | 217248篇 |
免费 | 1815篇 |
国内免费 | 515篇 |
专业分类
化学 | 117747篇 |
晶体学 | 3503篇 |
力学 | 9181篇 |
综合类 | 4篇 |
数学 | 21464篇 |
物理学 | 67679篇 |
出版年
2021年 | 1819篇 |
2020年 | 2059篇 |
2019年 | 2250篇 |
2018年 | 3067篇 |
2017年 | 3158篇 |
2016年 | 4482篇 |
2015年 | 2530篇 |
2014年 | 3926篇 |
2013年 | 9007篇 |
2012年 | 7495篇 |
2011年 | 8898篇 |
2010年 | 6563篇 |
2009年 | 6569篇 |
2008年 | 8431篇 |
2007年 | 8071篇 |
2006年 | 7868篇 |
2005年 | 7124篇 |
2004年 | 6467篇 |
2003年 | 6024篇 |
2002年 | 5885篇 |
2001年 | 7457篇 |
2000年 | 5404篇 |
1999年 | 4195篇 |
1998年 | 3130篇 |
1997年 | 3149篇 |
1996年 | 2890篇 |
1995年 | 2676篇 |
1994年 | 2635篇 |
1993年 | 2455篇 |
1992年 | 2997篇 |
1991年 | 3122篇 |
1990年 | 2912篇 |
1989年 | 2890篇 |
1988年 | 2818篇 |
1987年 | 2761篇 |
1986年 | 2564篇 |
1985年 | 3183篇 |
1984年 | 3272篇 |
1983年 | 2690篇 |
1982年 | 2692篇 |
1981年 | 2440篇 |
1980年 | 2397篇 |
1979年 | 2699篇 |
1978年 | 2918篇 |
1977年 | 2876篇 |
1976年 | 2713篇 |
1975年 | 2569篇 |
1974年 | 2571篇 |
1973年 | 2583篇 |
1972年 | 1747篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
M. A. Mikhaleva B. M. Bolotin T. A. Kizner E. S. Serebrykova 《Chemistry of Heterocyclic Compounds》1994,30(1):79-81
We have synthesized 5-alkyl(alkoxy)-2-(o-lzydroxy-p-alkoxyphenyl)pyrimidines and considered the effect of the OH group on the inesomorphism. We have found that in binuclear o-hydroxyarylpyrimidines, an ortho OH group forming an intramolecular hydrogen bond increases Tmp, inhibits the appearance of nematic properties, and promotes the appearance of a smectic A.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 1, pp. 90–92, January, 1994. 相似文献
12.
The electron-impact mass spectra of a number of phenylpropanoids and iridoid glycosides containing a phenylethanoid fragment in their structure have been studied. This has revealed features of the formation of fragments of 4-hydroxyphenylethyl and 3,4-dihydroxyphenylethyl alcohols and also of fragments of phenylethylamine and indolylethylamine derivatives present in the structures of the compounds investigated. 相似文献
13.
14.
15.
N. I. Khamidov B. T. Kadyrov N. T. Ul'chenko A. Sh. Isamukhamedov A. I. Glushenkova 《Chemistry of Natural Compounds》1994,30(4):430-433
The phsicochemical indices and the fatty-acid and triacylglycerol compositions of cottonseed and palm oils, of cottonseed
oil hydrogenate, and of compositions based on them have been determined with the aid of IR and UV spectroscopies, GLC analysis,
and chemical transformations. The compositions and amounts of the main classes of lipids in the initial oils and the hydrogenate
have been studied. It has been found that in the process of hydrogenation the amount of oxygenated components falls.
The work was conducted with the financial support of the Uzbek Fund for Fundamental Investigations. 相似文献
16.
S. O. Kolusheva B. A. Salakhutdinov T. F. Aripov L. P. Vernon 《Chemistry of Natural Compounds》1994,29(4):523-525
It has been shown by the ESR of spin probes that thionin initially interacts with with negatively charged membranes electrostatically and then passes into the membranes to a depth comparable with the length of the hydrophobic sections of the protein loops.Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Brigham Young University, Provo, Utah, USA. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 594–597, July–August, 1993. 相似文献
17.
T. A. Beu 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(3):263-266
New analytical formulas for the torsionL-tensor are reported, which are used in molecular normal mode analysis calculations for the nonlinear transformation of the force constants from internal coordinates to normal coordinates. The proposed formalism exhibits a relative simplicity as compared to previous reported results. Sample calculations for methanol and hydrazine are presented. 相似文献
18.
The microhardness and content of carbon in electroplated gold coatings were studied as influenced by the operation time of citrate and citrate-phosphate gold-plating electrolytes. Such physicomechanical properties as porosity, microhardness, internal stress, plasticity, and microstructure of electroless-plated and electroplated nickel coatings were studied and analyzed. 相似文献
19.
V. O. Tarasov 《Journal of Mathematical Sciences》1991,54(3):958-967
A mixed boundary-value problem for the nonlinear Schrödinger equation and its generalization is studied by the method used for the inverse scattering problem. A connection is established between conservation laws and boundary conditions in integrable boundary-value problems for higher nonlinear Schrödinger equations. It is shown that the generalized boundary-value problem requires a joint consideration of regular and singular solutions for the nonlinear Schrödinger equation with repulsion.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 169, pp. 151–165, 1988. 相似文献
20.